I select a large number of albums in the right pane and choose the "Remove Perfect Albums" plugin. After some amount of time, the colored pinwheel starts and CPU usage goes to 0. Apple's "Force Quit" window reports MusicBrainz Picard not responding.

If I select small batches (<100 albums) at a time, things complete normally, but over some size things eventually hang up.

Never had this problem with 1.2 but has occurred with all recent versions of 1.3 daily builds.

Attached is an Activity Monitor spin dump and process sample while it was hung.